In general, multi-view video coding (MVC) processes image sequences of respective views obtained from a plurality of cameras. The cameras are arranged so that there is a difference in distance and direction with respect to the same object. Multi-view images obtained through the cameras are different depending on the direction in terms of the degree of reflection of light at the surface of the same object, but the images of the respective views are highly correlated with each other. Due to the former characteristics of the multi-view images, there is a difference in brightness and chrominance between the images of respective views with respect to the same object, and thus the former characteristics must be considered in order to increase a coding efficiency of the multi-view video coding. Also, the coding efficiency of the multi-view images can be increased using the latter characteristics of the multi-view images.
In multi-view video coding that is being actively standardized, a method is investigated that increase the coding efficiency in consideration of the above two characteristics of the multi-view images on the basis of the conventional international standard for moving picture coding, H.264/MPEG-4 part Advanced Video Coding (hereinafter referred to as H.264/AVC). In the multi-view video coding that is being actively standardized, a method specified in the H.264/AVC is proposed for prediction of motion information such as a motion vector (MV). The MV prediction method specified in the H.264/AVC is based on the assumption that a motion vector MV of the current block obtained through temporal motion estimation (ME) is similar to a motion vector of a neighbor block.
That is, in the H.264/AVC, motion vectors MVN of neighbor blocks is used to obtain a motion vector predictor MVP, and then a motion vector difference MVD is obtained by subtracting the motion vector predictor from the motion vector of the current block. Then, not the motion vector MV of the current block obtained through motion estimation, but the motion vector difference MVD is transferred to a decoder.
Also, in the H.264/AVC, if there are multiple neighbor blocks for the current block, an intermediate value of all or some of the motion vectors of the neighbor blocks and the obtained intermediate value is used as the motion vector predictor of the current block.
However, in the conventional multi-view codec (MVC), a value for each anchor slice is coded so that each GOP (Group of Picture) has one disparity value, the position is at an anchor slice header, and a non-anchor slice is derived from the previous anchor slice and the next anchor slice on a time axis from the corresponding anchor slice, which causes an unnecessary disparity value to be obtained.
Also, because disparities, i.e., displacements between images taken from different views are not identical but are similar, the coding amount can be minimized through the differential coding of the disparities. This, however, is not considered at all, and thus there is a limit in increasing the coding efficiency.